Subdivisions get capital-intensive fast, so the financing challenge you’re anticipating is real for most developers, even in the U.S.A few approaches I’ve seen work in similar situations:Phase financing instead of trying to fund the whole thing at once.Some lenders (private or institutional) will fund infrastructure and horizontal work in stages as lots are pre-sold.

PLUMBING — SUPPLY LINESRemove all accessible galvanized supply lines in basementInstall PEX trunk and branch system to each unitNew main shutoff and individual unit shutoffs (label by unit)Proper supports, labeling, and pressure testNo in-wall work unless absolutely necessaryPLUMBING — DRAINSReplace all horizontal cast-iron drain lines in basement with PVCReplace only visibly failed vertical sectionsAdd minimum one accessible cleanoutCheck all vent stacks in atticInsulate exposed vent stacks as neededTie into existing stack and sewer lateralELECTRICALRemove abandoned/exposed knob & tube in basement and attic onlySecure open junction boxes, cap unused wiresPanel tighten, label, safety checkReplace unsafe breakers if found (no panel replacement unless quoted separately)Install basic LED pull-chain or strip lighting in basement common areasWATER MANAGEMENTSeal visible foundation penetrations and cracks (interior)Improve grading where soil slopes toward foundationAdd/extend downspouts to discharge away from structure

I think your horizontal axis is not helpful.

No vertical or horizontal projection, machinery, device or receiver of any type,including satellite dishes, shall be attached in, around or upon any part of thePremises or the property without Landlord's written consent.12.

The vertical stretches will likely last longer than horizontal.  

One of these days he will hustle the wrong individual and he will find himself in a permanent horizontal position.

So the scaling would have to be "vertically" as in - move to a bigger, 1031 to a more expensive property over time, rather than "horizontally" to more properties?

One can do short plats etc like Horizontal Regimes in say Charleston SC over the counter but thats just 4 units and under. 

It will amost certainly turn horizontally and run the perimeter of the footing,   and if the home is on a slope there may be a surface or subsurface (pipe ending in a dry well of some sort) exit drain from it,   search the lowest part of the lot edge.   

If it is damage caused by tenant (unlikely for good tenants) then possibly legit    If it has just got old or failed due to age, then they cannot charge the tenant  Depending on age of tub, they cannot charge to touch up paint the tub.Depending on the quality of the blinds, 10 years could be their expected lifetime   For example those 1” aluminum horizontal blinds are lucky to last 10 years    Good verticals blinds can last much longer.If they cannot produce a move-in check list or photos documenting the condition at move-in, they cannot charge for anything as how can they show it was not existing at move-in?